CA2550466A1 - Polyester fiber scrim and method for making same - Google Patents

Abstract

Self-supporting scrim or web structure, which is readily thermopleated, is provided for use in filter applications. The self-supporting scrim has very high porosity. When pleated and deployed for filter applications, the scrim or web structur e retains the shape of pleats and contributes minimally to airflow resistance. The scrim o r web structure is fabricated from synthetic fibers and latex binders using a wet laid process.

Claims (20)

1. A wet-laid, high porosity synthetic scrim composed of polyester fibers and a synthetic latex binder, wherein the synthetic latex binder has a softening temperature lower than the softening temperatures of the polyester fibers and wherein the synthetic scrim is mechanically shaped and then thermoplastically set in a self-supporting shape.

2. The scrim of claim 1 in which the polyester fibers comprise 65% to 85% of the weight of the scrim and the synthetic latex binder comprises 15% to 35% of the weight of the scrim.

3. The scrim of claim 2 in which the polyester fibers have a thickness in the range of about 6 denier to about 15 denier and a cut length of about 0.5 inch to 1.5 inches.

4. The scrim of claim 3 in which the synthetic latex binder is a thermoplastic acrylic resin with a softening point between 200°F and 300°F.

5. The scrim of claim 4 in which the basis weight is in the range of 1.4 oz/yd2 (47 g/m2) to 2.6 oz/yd2 (88 g/m2).

6. The scrim of claim 5 that has a Frazier porosity in the range of 700 to 1050 cfm/ft2.

7. A multilayer layer filtration media formed by deposing one of a melt blown polypropylene fibers layer, a glass microfiber layer, and a polypropylene nanofibers layer on one surface of the scrim of claim 6, thereby forming a dual layer filtration media.

8. The multilayer layer filtration media of claim 7 wherein one of a melt blown polypropylene fibers layer, a glass microfiber layer, and a polypropylene nanofibers layer, is sandwiched between the scrim of claim 6 and another scrim, thereby forming a three layer filtration media.

9. The multilayer layer filtration media of claim 7 configured as a self-supporting, pleated filtration media element that is mechanically pleated and whose geometry is thermoplastically set by heating at least a portion of the mechanically pleated scrim to a temperature of about 250°F to 300°F.

10. The multilayer layer filtration media of claim 7 configured as a self-supporting, pleated filtration media element that is mechanically pleated and whose geometry is thermoplastically set by heating at least a pleat tip of the mechanically pleated scrim to a temperature of about 250°F to 300°F.

11. The scrim of claim 2 in which the polyester fibers comprise a blend of different thicknesses and cut lengths.

12. The scrim of claim 11 in which the polyester fibers are a blend of 6 denier 1/2" and 15 denier 1 1/2" polyester fibers.

13. The scrim of claim 12 in which the amounts of 6 denier to 15 denier polyester fibers are in the ratio of about 4:1 to about 19:1.

14. The scrim of claim 12 in which the amounts of 6 denier to 15 denier polyester fibers are in the ratio of 9:1 and the thermoplastic binder content is about 25% by weight of the total weight of the scrim.

15. The scrim of claim 11 that has a Frazier porosity in the range of about 750 to 970 cfm/ft2.

16. A method for making a shaped filter media element that is self-supporting, the method comprising:

obtaining a scrim comprising polyester fibers and a synthetic latex binder, wherein the latex binder has a softening temperature lower than the softening temperatures of the polyester fibers;
mechanically shaping the scrim to a desired shape; and thermoplastically setting the mechanically shaped scrim to retain the desired shape

17. The method of claim 16, wherein obtaining a scrim comprising polyester fibers and a synthetic latex binder, comprises making the scrim by a wet-laid process.

18. The method of claim 16, wherein mechanically shaping the scrim to a desired shape comprises mechanically pleating the scrim.

19. The method of claim 18, wherein thermoplastically setting the scrim in the desired shape comprises heating at least a pleat tip of the mechanically pleated scrim to a temperature of between about 200°F and about 300°F.

20. The method of claim 16, wherein thermoplastically setting the scrim in the desired shape comprises heating at least a portion of the mechanically shaped scrim to the softening temperature of the latex binder.